HE (3:12 



HB 1323 
■ 14 P4 
Copy 1 



Variation in the Rate of Infant Mortality 

in the United States Birth 

Registration Area 



RAYMOND PEARL. Ph.D. 
BALTIMORE 



Reprinted from the Transactions of the Eleventh Annual Meeting of 
the American Child Hygiene Association, St. Louis, October 11-13, 1920. 



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VARIATION IN THE RATE OF INFANT MORTALITY IN THE 
UNITED STATES BIRTH REGISTRATION AREA^ 

RAYMOND PEARL, Ph.D., BalUmore 

Until recently it has been impossible to discuss on any accu- 
rate or satisfactory basis the infant mortality of any considerable 
portion of the United States. This difficulty has arisen from the 
fact that except in a few localities, notably some of the New Eng- 
land States, there has been in the past no adequate system of birth 
registration. The most accurate practical method of stating the 
force of infant mortality is to relate the number of deaths of infants 
under one year of age in a given time unit to the number born in the 
same time unit. Consequently, one needs accurate birth statistics 
before infant mortality can be adequately discussed. 

It is a matter of great satisfaction to everyone interested in 
the subject of infant mortality that at last there is well established 
a Birth Registration Area for the United States, and four annual 
reports on Birth Statistics of this area have been issued to date by 
the Census Bureau. We are well embarked now on the policy of 
adequate birth statistics for the country and unquestionably with- 
in a comparatively few years the Birth Registration Area will cover 
the major portion of the country as the Death Registration Area 
now does. In the short period since the Birth Registration Area 
has been established its growth in extent has been gratifyingly 
rapid. The first report on birth statistics for the year 1915 com- 
prised data from an area including approximately 31 per cent of 
the population of the country. The 1918 birth statistics report 
gives data from an area including 53 per cent of the population. 
This furnishes a sufficient volume of material so that one may 
begin the mathematical analysis of some of the problems of infant 
mortality with some assurance of reaching valid conclusions. 



» Papers from the Department of Biometry and Vital Statistics, School of 
Hygiene and Public Health, Johns Hopkins University, No. 18. This paper, which 
is a preliminary and condensed abstract of a much more detailed investiga- 
tion of the subject, shortly to be published elsewhere. 



The purpose of the present paper is a modest one. It aims 
simply to present briefly some of the facts of variation in rate of 
infant mortality in different geographic or demographic units of 
the population. The first step in the solution of any problem is 
obviously a clear definition of the problem itself. We shall see, as 
we pass from city to city, town to town, or rural county to rural 
county, that the rate of infant mortality varies greatly. In a hypo- 
thetical commonwealth where the most perfect administrative con- 
trol over infant mortality possible or conceivable had been attained, 
this variation would largely disappear, the only residue of diversity 
between communities in respect of infant mortality being such as 
arose purely by the operation of chance, that is, from random 
sampling, or from uncontrollable environmental factors, such as 
climate or soil. Now, with the actually existing condition of vari- 
ation between different communities in respect of infant mortality, 
it is obvious that there must be particulate and presumably deter- 
minable reasons for each particular difference which exists. Oper- 
ating on a basis largely of empiricism and a 'priori reasoning, efforts 
to reduce infant mortality have in the past been attended with 
considerable success. Also, with the advance of general sanitation 
the death rate under one year of age has fallen enormously. 
Greenwood ' quotes some interesting figures on the point from Farr, 
which we may well reproduce here to show how enormous has been 
the Improvement. 

Period 1730-49 1750-69 1770-89 1790-1809 1810-29 

Percentage Deaths under 5 years.... 74.5 63.0 51.5 41.3 31.8 

But after such a decline as these figures indicate the continu- 
ation of the business offers a difficult problem to the administra- 
tive official, whose procedures are grounded essentially only on the 
two pedestals of what he thinks has worked in the past and what 
he believes logically ought to work. The easy part of the conflict 
has happened and is in the past. To continue the good fight with 
the same relative measure of success, one presently must needs 
know more precisely than is now known the pattern of the causal 
nexus which controls and determines the rate of infant mortality. 
And it is real knowledge, not a priori logic, that is wanted. Let a 



' Greenwood, M. Infant mortality and its administrative control. Eugenics 
Rev. Oct. 1912, pp. (of reprint) 1-23. 



QiSt 

Autiioi 

V.fM -0 1922 



single example illustrate. It has been maintained that excessive 
infant mortality is primarily the resultant of the so-called "degrad- 
ing influences" of poverty, and such a contention stirs a warmly 
sentimental feeling of agreement in the minds of the well-meaning 
public zealous to do good. This relationship obviously ought to be 
true, therefore to a too-common type of mind it must be and is true. 
But Greenwood and Brown' in what may fairly be regarded the 
most thoroughly sound, critical and penetrating contribution 
which has yet been made to the problem of infant mortality are 
unable "to demonstrate any unambiguous association between pov- 
erty . . . and the death rate of infants." 

The plain fact is that before control or ameliorative measures 
can be applied with the maximum of efficient economy to the gen- 
eral public health problem of infant mortality we must know a 
great deal more than we now do about the factors which induce 
spatial and temporal differences in the rate of that mortality. But 
first we must get an adequate conception of the magnitude and 
character of the differences themselves. Let us, therefore, turn to 
the examination of the facts regarding variation in infant mortal- 
ity in the United States Birth Registration Area. 

Variation Data 

In this work we have studied the variation in the rate of infant 
mortality (deaths per thousand births) for the following groups: 

1. Total population in cities of population of 25,000 or over In 1910. 

2. Total population in cities of under 25,000 population in 1910. 

3. Total population in rural counties of registration states. 

4. White population in cities of population of 25,000 or over in 1910. 

5. White population in cities of under 25,000 population. 

6. White population in rural counties of registration states. 

7. Colored population in cities of population of 25,000 or over in 1910. 

8. Colored population in cities of under 25,000 population. 

9. Colored population in rural counties of registration states. 

In order to make possible a better appreciation of the nature of 
the frequency distributions Figure 1 has been prepared. This 
shows for the year 1918 the frequency polygons for the total popu- 



» Greenwood. M. and Brown, J. W. An examination of some factors Influenc- 
ing the rate of infant mortality. Jour. Hyg. Vol. XII. pp. 5-45, 1912. 



lation of (a) cities of 25,000 and over, (b) cities of under 25,000, 
and (c) rural counties. 




so aio f30 £50 erO <?90 310 330 



rate: or infant noRTRLiTv 



Fig-. 1. Frequency polygons showing variation in the rate of infant mortal- 
ity In 1918 for the total population of (a) cities of 26,000 and over, (b) cities 
of under 25,000, and (c) rural counties. 

This diagram is fairly representative of all the distributions. 

The most striking immediately observable feature of these dis- 
tributions is the great range of variation which they exhibit. For 
example, in 1918 the 236 cities of under 25,000 inhabitants showed 
infant mortality rates ranging all the way from the class 40-59 
deaths per thousand births to the class 300-319 deaths per thou- 
sand births. The range of variation is even greater than this in the 
case of the distributions for the colored population. These extra- 
ordinarily large ranges of variation demonstrate perhaps more 
clearly than could be done in any other way the opportunity which 
exists for effective administrative control and reduction of infant 
mortality. If there are communities, as there are in plenty, show- 



ing infant mortality rates under 100 deaths per thousand births it 
suggests at once that it is possible if the right measures are syste- 
matically and effectively applied to reduce the infant mortality in 
those other communities showing very high rates to something like 
the level of these at present more fortunate communities. 

TABLE I. 

Constants of variation in rate of infant mortality 
(deaths under 1 per 1,000 births) 



Group 



Standard 
deviation^ 



Skewness 



Cities over 25,000S Total, 1915 

1916 

1917 

" 1918 

Cities under 25,000i, Total, 1915... 
1916.., 
1917... 
1918... 

Rural counties, Total, 1915 

1916 

1917 

1918 

Cities over 25,000S White. 1917 

1918 

Cities under 25,000i, White, 1917. 
1918., 

Rural counties, White, 1917 

1918 

Cities over 25,000^ Colored, 1917.., 
1918.. 

Cities under 25,000^, Colored, 1917 
1918 

Rural counties. Colored, 1917 

1918 



104.49- 

102.53- 

99.58- 

107.78; 

100.98- 

104.23- 

99.24- 

111.61: 

• 83.07- 
85.28- 
82.01- 
84.43; 

92.22- 
102.59; 

98.46- 

114.62; 

86.21- 
85.90; 

202.59- 
216.67; 

213.08- 
217.69] 

134.76- 
147.26- 



1.78 
1.67 
1.32 
1.41 


102.76 

103.24 

98.00 

105.50 


1.68 
1.75 
1.32 
1.66 


97.95 
101.03 

94.74 
104.17 


.85 
.90 
.52 

.57 


79.54 
82.15 
78.96 
80.97 


2.02 
2.00 


92.14 
99.23 


2.75 
4.17 


97.50 
113.33 


1.07 
1.27 


84.24 
83.75 


8.88 
11.15 


194.00 
214.00 


9.92 
11.46 


228.00 
225.00 


2.55 
2.92 


127.25 
134.59 



26. 14 -J 
24.69; 
23.45; 
25.07; 

30.81- 
32.38; 
29.94; 
37.78; 

23.95; 
25.94; 
25.71- 
28.40; 

15.60- 

15.42; 

20.82- 

31.49; 

24.15- 
28.90 ; 

68.45- 
85.87; 

74.96- 
86.65; 

57.37- 
66.15- 



■1.26 

:i.i8 

■ .93 
1 1.00 

■1.18 
■1.24 



- .60 

'■ .63 

'■ .37 

: •*<> 

■1.43 
;i.42 

■1.95 
■2.95 



: .90 

■6.28 



7.01 
■8.10 



■1.80 
^2.06 



1 In 1910. 

2 In concrete units, I. e., rate of deaths under 1 per 1,000 births. 



-f .3148 
— .0786 
-I-.2455 
-I-.3237 

-)-.1934 
-i-.2217 
4-. 4840 
-1-.5625 

-I-.3204 
-[-.3536 
-I-.2833 
-I-.4328 



-f-.1799 
-I-.2802 



-I-.4984 
-f .5819 



In Table I are presented the chief physical constants' of the 
distributions of variation in infant mortality. These constants 
have been determined by the method of moments from the original 
raw data." 



* For a very brief and summarized Introduction to the modern mathematical 
treatment of frequency curves see Pearson, K., "Tables for Statisticians and 
Biometricians," 1914, pp. Ix to Ixx. References to the basic literature on the 
subject will be found there. 

"I am greatly Indebted to my assistant, Mrs. Charmlan Howell, for aid In 
the arithmetical work of this paper. 



The constants tabled are: 

1. The arithmetic mean. 

2. The median. This nleasures the value above and below which 

exactly half of the variates occur. 

3. The standard deviation. This constant measures In absolute units 

the degree of "scatter" or variation exhibited by the distribution. 

4. The skewness. This constant measures the degree of asymmetry of 

a frequency distribution. If a distribution is perfectly sym- 
metrical on both sides of the niean so that If folded over upon the 
mean as an axis the two limbs would exactly coincide, the value 
of the skewness is zero. 

From the data presented in Table I. the following points are 
to be noted : 

1. There is no certainly significant decline in the mean value 
of the rate of infant mortality during the four years covered by 
these statistics in any of the demographic units considered. 

2. In 1918 there was a general tendency towards an increase 
in the mean rate of mortality over that which obtained in 1917. 
This increase is unquestionably to be attributed to the influenza 
epidemic of the autumn and winter of 1918. A careful examina- 
tion of the rates by months will convince one that the mortality 
of infants increased very materially during the period of the epi- 
demic. Whether this increased number of deaths was truly to be 
charged to influenza does not concern us here. The important fact 
is that the rate of infant mortality markedly increased coincidently 
with the existence of the epidemic. It is noteworthy that this in- 
crease in the infant mortality rate in 1918 is practically confined 
entirely to the cities. The rural counties, whether for white or col- 
ored or total population, show little or no change in 1918 as com- 
pared with 1917. 

3. There is no unequivocal difference in the mean rates of 
infant mortality in the larger as compared with the smaller cities. 
Considering the largest differences in mean rates for total popu- 
lations in cities of 25,000 and over as compared with cities of under 
25,000 there is no difference which is as much as even three times 
its probable error. 

4. The mean rates of infant mortality are notably smaller in 
the rural than in the urban areas. This fact has, of course, long 
been well known. The first writer on vital statistics, in the sense 
in which we now understand that subject. Captain John Graunt, 



more than 250 years ago pointed out that rural communities ex- 
hibited generally a lower rate of mortality than urban communi- 
ties. The difference between urban and rural rates of infant mor- 
tality is reflected just as clearly in the high absolute rates of the 
colored population as it is in the lower rates of the white population. 

5. The mean rates of infant mortality are, roughly speaking, 
something like twice as high for the colored population as for the 
white population in each of the demographic units considered, and 
at all times. This again is a fact in general well known, but here 
we have precise figures on the point, with probable errors, which 
show definitely how tremendously poorer the negro baby's chances 
of surviving the first year of life are than the white baby's. 

6. The cities of over 25,000 exhibit distinctly less variation in 
respect of infant mortality than do either the smaller cities (under 
25,000) or the rural counties. The smaller cities and the rural 
counties exhibit about the same degree of variation relative to their 
means, but absolutely, in terms of standard deviation, the rural 
counties show less variability than the cities under 25,000. The 
colored distributions exhibit a much higher degree of variation in 
respect of infant mortality however measured, whether absolute or 
relative, than do the white populations. In general, it may fairly 
be assumed that the greater the variation exhibited by a given class 
of the community in respect of infant mortality, the greater the 
chance of effective control and reduction of the average infant 
mortality by administrative measures. There can be no question 
that there is no field which offers so great opportunities in this 
direction as the colored population. 

7. The skewness is seen to be positive in sign in every case but 
one. In that case (1916, cities over 25,000 total) the skewness is not 
significant in comparison with its probable error. With this excep- 
tion the curves tend to tail off more gradually and farther towards 
the right end than towards the left end of the range. In other words, 
the rate of infant mortality in these different American demo- 
graphic units tends generally to distribute itself in a substantially 
unsynmietrical fashion about the mean, extremely high rates oc- 
curring more frequently than correspondingly low rates. This fact 
might perhaps be taken to indicate that the task confronting the 
administrative control of infant mortality in the United States, and 



yet to be accomplished, is even greater than what has already been 
accomplished in the past, great and worthy of commendation as 

that is. 

Data on the Idmitatioiis to Administrative Control of Infant Mortality. 

We have seen that there is a high degree of variation in the 
rate of infant mortality as we pass from community to community. 
Some communities have infant mortality rates several times higher 
than those prevailing in other communities of the same size. This 
creates the presumption at once that proper administrative activity 
might reduce the rates of these abnormally high communities to a 
level commensurate with those found in the lower group. It is the 
purpose of this section of the paper to examine this presumption 
critically. 

At the outstart it is evident that there are some causes of in- 
fant mortality which are, in their very nature, beyond hope of 
effective practical human control. Thus, children born with marked 
congenital hydrocephalus will presently die, in spite of anything 
the health officer can do, no matter how active and intelligent he 
may be. There are other causes of death falling in essentially the 
same category in this respect. 

Not as any final or dogmatic settlement of the matter, but 
rather as a tentative first approximation made for the purpose of 
seeing whether any suggestive lead may appear, I have ventured 
to attempt to classify the principal causes of mortality in the first 
year of life into two groups. The first of these groups aims to in- 
clude those important causes of infant mortality which are either 
(a) actually now effectively controlled by the efforts of health 
officials, either directly, or indirectly through general sanitary and 
hygienic improvements, or (b) are obviously capable theoretically 
of control and amelioration if sufficient pains be taken. The sec- 
ond group aims to include those causes of infant deaths which are 
either (a) in the nature of the case, out of the range of effective 
practical, direct control or amelioration, or (b) are not in fact now 
controlled in any appreciable degree. Let us see what such a classi- 
fication, to a first approximation, looks like. 



Tentative Olassiflcation of Principal Causes of Infant Mortality. 

A. Causes of death actually now well B. Causes of death not controlled 
controlled, or capable theo- Tuberculosis of the lungs 

retically of direct control in Tuberculous meningitis 

greater or less degree: Other forms of tuberculosis 

Measles Syphilis 

Scarlet fever Organic diseases of the heart 

Whooping cough Malformations 

Diphtheria and croup Premature birth 

Dysentery Congenital debility 

Erysipelas Injuries at birth 

Tetanus 

Meningitis 

Convulsions 

Acute bronchitis 

Pneumonia 

Bronchopneumonia 

Diseases of the stomach 

Diarrhea and enteritis 

External causes 

One realizes that it is a bold thing even to set down such a 
classification as the above. It is certain to stir up the rancor of 
extremists in both directions. But extremists are nearly always 
wrong. Calm and unprejudiced persons will admit that some such 
classification as that here attempted is possible. Perhaps some 
further discussion of this classification may make clearer its point 
of view, and may win at least that measure of agreement with it 
which will at least permit the consideration of the discussion of its 
consequences which follows. 

Taking column A first, presumably no competent health official 
would deny that the first diseases in the list (scarlet fever, whoop- 
ing cough, diphtheria and croup, and dysentery) have been, can be, 
and are in greater or less degree effectively controlled in respect 
both of their incidence and their mortality. With this same group 
clearly belongs also diarrhea and enteritis, and convulsions, on 
the justifiable assumption that in the vast majority of cases convul- 
sions in infants are consequent upon violent enteric infections, 
which clearly belong in the controllable class. Diseases of the 
stomach, as causes of death under one year of age, again in the vast 
majority of cases undoubtedly mean infection — filth diseases in 
short — which come in the same category, so far as concerns con- 
trol, as diarrhea and enteritis. Regarding the rest of the diseases 
in the A group (erysipelas, tetanus, meningitis, acute bronchitis, 



pneumonia, bronchopneumonia, and external causes) the point of 
view of which led to their inclusion here is as follows : If the envir- 
onmental conditions surrounding the infant in the community and 
in the home, and the care given it, were made as favorable as they 
might be made, and actually are in the homes of the hygienically 
intelligent well-to-do, the death rate from each of these causes 
would be enormously reduced relatively in comparison with what 
it actually is. As a matter of fact visiting child welfare nurses 
are doing a mighty work in just this direction in many communi- 
ties. They teach parents how to care for their infants, protect them 
from these infections, and nurse them to a non-fatal issue in many 
cases if they do get infected." 

Now for the B column. The first three items are the various 
forms of tuberculosis. The fanatic will no doubt promptly 
assert that nothing is so easily and readily controllable as these. 
But let us make haste slowly and remember certain things: 
First, that we are here talking about deaths under one year of age, 
that is fatal tuberculosis in the first months of life; and second, 
that our classification premises, in specific and stated terms, direct 
control, that is control through agencies acting directly upon the 
infant or his environment. Theoretically it is possible to reduce 
materially the mortality under 1 from tuberculosis. If every child 
born to tuberculous parents was instantly and ruthlessly removed 
from the home from the moment of birth, and reared in an environ- 
ment where no contact with tubercle bacilli was possible, unques- 
tionably enormously fewer infants would develop tuberculosis in 
the first year of life than now do. A recent paper by Bernard 
and Debre' furnished an instructive example, showing in a single 
case how a child removed at II/2 months from its tuberculous 
mother, threw off completely its own tuberculosis. But practically 
it is perfectly clear that neither in the past has there been, nor in 
the present is there, nor probably for some time in the future will 
there be rigid isolation of offspring from tuberculous parents to an 



®No "6ttetj;who knows at first hand what child- welfare public health nursing 
is actually accomplishing in these directions will question the putting of these 
diseases in the controllable column. Their mortality rate can be materially 
reduced if communities will take the trouble to go intelligently about it. 

^Bernard L,., and Debre, R. Bull. Soc. Med. des Hosp. T. 44, p. 1658. 1920. 
Rev. in Jour. Am. Med. Assoc. March 19, 1921, p. 824. See also paper In the pres- 
•ent volume of these Transactions, on "Prevalence and Management of Tubercu- 
losis in Infancy," by T. C. Hempelmann, p. 



extent or degree suflficient to influence the infant mortality from 
tuberculosis, in the entire Registration Area of the United States, 
by as much as one unit of the death rate. The mortality from 
tuberculosis under 1 year of age has to be sure declined during 
the past 40 or 50 years but no more rapidly than the general curve 
of tubercular mortality at all ages. But many persons fail to find 
any evidence that control measures have had anything to do in 
bringing down the general tuberculosis death rate. In this connec- 
tion a recent paper by Given' on the influence of administrative or 
control measures upon the course of tuberculous mortality in gen- 
eral is interesting. He says : "Statistics show us that, in spite of all 
that has been said and done for the prevention of tuberculosis, our 
efforts in regard to pulmonary tuberculosis have not been attended 
with the anticipated success. The decline in mortality from this 
cause dates from 1838, and has continued steadily ever since down 
to 1913. Koch's discovery of the tubercle bacillus in 1882 does not 
appear to have affected it in any way." 

I know of no evidence that anything now being done is sen- 
sibly influencing the rate of mortality from tuberculosis in infants 
under 1. Some individual physicians may have been particularly 
successful with a small number of tuberculous babies under his 
care. But statistically it means little in the toll of 2,501 deaths 
under 1 which tuberculosis is recorded to have taken in the Regis- 
tration Area of the United States in 1918. Actually if the truth 
were known the total would be much larger even than this. 

About fatal congenital organic diseases of the heart, congeni- 
tal malformations grave enough to be fatal in the first year of life, 
and fatal congenital debility there will probably be no dispute. 
The mortality from fatal congenital syphilis is again, like tubercu- 
losis, theoretically controllable." But practically and in fact, is it 
controlled? The writer feels extremely doubtful about it. 

Regarding premature birth, and injuries at birth, much the 
same reasoning applies, but with the additional consideration that 
presumably intelligent prenatal education of the mothers and 
improvement of prenatal environmental conditions would reduce 



* Given, D. H. C. Some deductions from the statistics on the prevention of 
pulmonary tuberculosis. Bull. Med. Jour. Feb. 12, 1921, pp. 225-226. 

» Cf. Jeans, P. C. Syphilis and Infant Mortality. Trans. Am. Assoc, for Study 
and Prev. Inf. Mortality. Vol. IX, p. 155. 



these mortality rates in some unknown, but probably not large 
degree. Actually, however, there is no tangible evidence that 
these causes of death are in effect administratively controlled in 
any appreciable degree in this country at this time. 

Finally it should be said that one occasionally important cause 
of infant mortality is omitted entirely from the classification. This 
is influenza. The reason for the omission is simply that the statis- 
tical discussion which follows is based upon 1918 mortality figures 

TABLE II — Showing the deaths under one year of age per 1,000 living 
births for (A) controllable, and (B) non-controlled causes of 
death in certain American cities of 100,000 population or over 
in 1910. 



City 



Births 
In 1918 



Deaths under one year 



A. From 
causes 
control- 
lable in 
some 
degree 



A. Rate 
of control- 
lable 
deatbs 



B. From 


B. Bate of 


causes 


not con- 


not con- 


trolled 


trolled 


deaths 



Rate per 
1,000 
births 

from all 
causes 



Bridgeport 

New Haven 

Washington 

Indianapolis 

Louisville 

Baltimore 

Boston 

Cambridge 

Fall River 

Lowell 

Worcester 

Detroit 

Grand Rapids .... 

Minneapolis 

St. Paul 

Albany 

Buffalo 

Bronx Borough . . . 
Brooklyn Borough . 
Manhattan Borough 
Queens Borough . . 
Richmond Borough 

Rochester 

Syracuse 

Cincinnati 

Cleveland 

Columbus 

Dayton 

Toledo 

Philadelphia 

Pittsburgh 

Scranton 

Providence 

Richmond, Va. . . . 

Seattle 

Spokane 

Milwaukee 



4,910 

4,869 

8,162 

6,196 

4,368 

15,143 

20,062 

2,672 

3,646 

3,286 

6,238 

27,036 

2,836 

8,704 

5,155 

2,153 

13,989 

16,763 

49,515 

59,227 

9,467 

2,677 

6,855 

4,352 

7,913 

20,699 

4,464 

3,282 

5,524 

43,408 

15,875 

3,139 

6,384 

3,840 

5,910 

2,194 

11,090 



226 


46 


190 


39 


399 


49 


270 


44 


239 


55 


1,225 


81 


1,092 


54 


144 


54 


403 


111 


302 


92 


212 


40 


1,296 


48 


110 


39 


198 


23 


160 


31 


96 


46 


866 


62 


496 


30 


2,232 


45 


2,855 


48 


389 


41 


113 


42 


283 


41 


265 


61 


326 


41 


963 


47 


163 


37 


109 


33 


186 


34 


2,876 


6d 


1,179 


74 


263 


84 


342 


54 


199 


52 


93 


16 


55 


25 


574 


52 



224 


46 


200 


41 


450 


55 


269 


44 


210 


48 


847 


56 


984 


49 


111 


42 


183 


50 


180 


55 


248 


47 


1,199 


44 


119 


42 


358 


41 


135 


26 


122 


57 


653 


47 


669 


40 


1,889 


38 


2,456 


41 


417 


44 


139 


52 


276 


40 


206 


47 


404 


51 


790 


38 


255 


57 


143 


44 


270 


49 


1,993 


46 


805 


51 


141 


45 


352 


55 


285 


74 


218 


37 


90 


41 


488 


44 



100 

90 

112 

93 

112 

14» 

115 

107 

180 

159 

97 

100 

86 

- 73 

87 

116 

121 

75 

90 

97 

93 

106 

92 

119 

104 

98 

101 

87 

94 

124 

139 

141 

123 

147 

61 

77 

106 



and inasmuch as that was a year in which the influenza mortality 
was abnormally heavy owing to the epidemic it was thought that 
it would be unfair to the general relationships exhibited to include 
this epidemic mortality. Presumably normal endemic influenza 
should be in the A group, on the same reasoning as the pneumonias. 
With so much of explanation as to the point of view of this 
classification let us examine some of its statistical consequences. 
These consequences I have tested in a preliminary way upon the 
birth and death data for certain large cities and the registration 
states in 1918. There were found to be 37 large cities included 
in both Birth and Death Registration Areas in that year, and 
20 states. For each of these cities and states the births were taken 
from 1918 Birth Statistics and the deaths under one year of age 
according to causes from Table II of the 1918 Mortality Statistics. 
From these data the rates per thousand living births for all class 
A and all class B diseases were separately calculated. The results 
are set forth in Tables II and III. 



TABLE in — Showing the deaths under one year of age per 1,000 living 
births for (A) controllable, and (B) non-controlled causes of 
death in twenty registration states. 





Births 
in 1918 




Deaths under one year 




state 


A. Prom 
causes 
control- 
lable in 
some 
degree 


A. Rate 
of con- 
trollable 
deaths 


B. From 
causes 

not con- 
trolled 


B. Rate 
of not 

con- 
tiolUi! 
deaths 


Rate 
per 
1.000 
births 
from all 
causes 




36,971 

64,385 

39,117 

62,338 

16,798 

34,113 

95,640 

91,011 

55,941 

9,642 

242,155 

75,525 

124,586 

220,170 

15,499 

14,478 

7,507 

63,062 

25,682 

60,867 


1,755 

2,482 

1.163 

2.325 

670 

2,531 

5,284 

3,496 

1,317 

451 

10,897 

2,850 

5,029 

14,506 

947 

308 

258 

2.529 

544 

1,854 


47 
39 
30 
1 37 
40 
74 
55 
38 
24 
47 
45 
38 
40 
66 
61 
21 
34 
40 
21 
30 


1,723 

2,520 

1,522 

2,328 

743 

1,730 

4,324 

3,760 

2,060 

499 

10,333 

2,319 

5,206 

10,295 

783 

474 

343 

2.448 

980 

2,334 


47 
39 
39 
37 
44 
51 
45 
41 
37 
52 
43 
31 
42 
47 
51 
33 
46 
39 
38 
38 


107 




87 




80 


Kentucky 


93 
101 


Maryland 

Massachusetts 


140 

113 

89 




71 


New Hampshire 

New York 


113 

97 
102 


Ohio 


94 


Pennsylvania 


129 
126 




64 




93 


Virginia 

Washington 


103 
69 

79 







In the last column of these tables the gross infant mortality 
rates from all causes of death have been inserted for comparison 
and to furnish the basis of certain discussions which will follow. It 
will be noted that the five boroughs of New York City have been 
treated as separate cities. This appears to be entirely justifiable, 
both on grounds of size, and of differentiation, any two of these 
boroughs being as much differentiated biologically and demo- 
- graphically as, for example, Minneapolis and St. Paul. 

The first point which strikes one in examining Tables 11 and 
III is that in the group of causes of death subject to our classifica- 
tion (which includes in most cases, as will be seen, something over 
90 per cent of all the mortality under one year of age) the con- 
trollable and uncontrolled causes are responsible for approxi- 
mately an equal degree of mortality. In other words, it appears 
that if any degree of justification attaches to the classification here 
suggested, the infant mortality beyond present control by adminis- 
trative measures is by no means a negligible fraction of the total 
infant mortality. On the contrary, it represents a substantial lower 
limit sensibly below which the health officer, no matter how zealous 
and intelligent his activities, may not hope to go at the present 
time. 

If there is a substantial moiety of the existing infant mortal- 
ity which is uncontrolled by administrative measures and is essen- 
tially unaffeected by the present or past application of such meas- 
ures, we should expect that the rate of mortality represented by this 
moiety would vary but little from city to city or state to state. 
As we have seen, the main reason why this part of the total infant 
mortality is beyond control is because it depends upon fundamental 
biological factors inherent in the parents and the infants. Clearly 
if this is so, whatever variation appears in this portion of the total 
infant mortality rate as we pass from community to community 
must arise from some combination of two factors; of which the 
first and less important is pure chance, that is, variation arising 
from random sampling purely; and of which the second is differ- 
ing racial and other biological characteristics of the populations of 
the several communities. We should expect the variation in the 
death rate from the class B group of causes to show very little vari- 
ation as compared either with the variation in the rate from class 



A causes or in the gross infant mortality rate from all causes. This 
a priori expectation is beautifully realized in the actual statistics. 

TABI/E IV — Frequency distributions of variation in rates of mortality under 
one per thousand births for (A) controllable, and (B) non- 
controlled causes. 





Cities 


States 


Rate 


A 

Causes 


B 

Causes 


All 
Causes 


A 
Causes 


B 

Causes 


All 
Causes 


15-24 


2 
5 
9 

12 
3 

2 
2 

1 

i 


i 

16 

i 13 

6 

1 


1 

1 

2 

1 9 

1 7 

6 

6 

1 

1 2 
1 2 
1 1 

i 


3 
3 
7 
3 
2 


2 
11 

7 




25-34 




35-44 




45-54 




55-64 


1 


65-74 






2 


75-84 


2 


85-94 










5 


95-104 


4 


105-114 


3 


115-124 




125-134 


2 


135-144 


1 


145-154 




155-104 




165-174 


1 


175-184 












Totals 


37 


37 


37 


20 


20 


20 



















TABLE V. 

Variation constants from the distributions of Table FV. 



(Inni]) 


Mean 


Median 


Standard 
deviation 




49.46 -f- 2.04 
47.30 ■+■ .90 
107.84 -+- 2.75 
42.00 ■+■ 2.17 
42.50 -+- .83 
97.00 + 3.03 


47.08 
46.15 
102.86 
40.71 
42.27 
95.00 


18.37 -f- 1.44 




8.09 -H .63 




24.78 -+- 1.94 




14.41 + 1.54 




5.52 -t- .59 




20.07 ■+■ 2.14 







It is seen that the class B causes of death, which are not prac- 
tically capable at the present time of administrative control or 
amelioration, exhibit less than one-half as much variation in the 
rate of infant mortality for which they are responsible, as we pass 
from city to city or from state to state, as do the class A causes of 
death, ivhich are capable of administrative control. This relation is 
true however the variation is measured. This is a novel result, of 
interest from several points of view. 



In the first place, the suggestion lies near at hand that if the 
class A causes of death, which are controllable, show such great 
variation relatively as they do, it must mark an approximately equal 
variability in the zeal, intelligence, and efficiency of the administra- 
tive health officials of these communities. Anyone at all familiar 
with the organization of municipal and state health departments 
in this country will find it extremely interesting to study in detail 
the entries of Tables II and III noting how the class A (con- 
trollable) and the "all causes" rates fluctuate up and down, while 
the class B (non-controlled) rates stay, with a very few excep- 
tions, so extremely constant. One will observe, with great satis- 
faction what splendid work is being done in some communities in 
holding down to a low level the infant death rate from controllable 
causes. Table II forms a real justification of the faith that is in the 
public health official of vision. It shows that the infant mortality 
from controllable causes can be kept down to a low level, and is 
in some communities. In the following cities (17 out of 37) the 
rate of infant mortality from the controllable causes of class A is 
actually lower than the rate from the non-controlled causes 
(class B) . 

New Haven Cincinnati 

Wlashlngton Columbus 

Worcester Dayton 

Grand Rapids Toledo 

Minneapolis Providence 

Albany Richmond 

Bronx Borough Seattle 

Queens Borough Spokane 
Richmond Borough 

These cities stand as examples of the fact that a considerable 
portion of the infant mortality rate can be controlled. 

Summary. 

This paper is a first biometric survey of the infant mortality 
statistics of the recently established Birth Registration Area. It is 
to be regarded as preliminary to certain analytical studies of the 
problem of infant mortality now in progress in this laboratory. 
The chief results of the paper are first to set forth and discuss 
some of the constants of variation in infant mortality in the differ- 
ent demographic units. This variation, which is large in amount, 
markedly and consistently skew in the positive direction, defines 



and throws into high relief the fundamental public health or admin- 
istrative problem of infant mortality. Why do the communities 
having rates of infant mortality higher than the average occupy 
that position? Is it from causes capable of human control, or from 
causes beyond the possibility of such control? A special prelimi- 
nary analysis of the data for cities of over 100,000, and the regis- 
tration states indicates that causes of death capable of administra- 
tive control are chiefly responsible for the variation observed in the 
total infant mortality rate, while those causes of infant deaths 
which, for fundamental biological reasons, are not sensibly in- 
fluenced or controlled by administrative measures, are a highly 
stable and constant factor from community to community, con- 
tributing little to the observed variability of the total infant mor- 
tality rate. In absolute terms, however, these causes of death not 
administratively controlled are responsible for roughly 40 per cent 
of the total infant mortality in the communities discussed. 



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